Process of lubrication for metal frictional surfaces



I N 1965 KENICHI NAKAMURA 3,217,834

PROCESS OF LUBRICATION FOR METAL FRICTIONAL SURFACES Filed June 14, 19632 Sheets-Sheet 1 F ag. 1

INVENTOR.

1965 KENICHI NAKAMURA 3,

PROCESS OF LUBRICATION FOR METAL FRICTIONAL SURFACES 2 Sheets-Sheet 2Filed June 14, 1963 Lubricant I Current, A Mater Oil 7 Non o Motor OilOrganic Phosphite Compound N 13,6. 10 amp -6. a p

PROCESS OF LUBRICATION FOR METAL FRICTIONAL SURFACES Kenichi Nahamura,12 Hara-cho, Bunlryo-lru,

Tokyo, Japan Filed June 14, 1963, Ser. No. 287,364 Ciairns priority,application Japan, June 22, 1962, 37/25,543, Patent 33/4,875 3 Claims.(Cl. 184-1) The present invention relates to a process of lubricationfor metal frictional surfaces wherein performance characteristics oflubricants are considerably improved by the flow of an electric currentbetween the frictional surfaces, so as to reduce the frictiontherebetween and to increase the resistance against abrasion of thefrictional surfaces.

It was believed that upon passing an electric current between thefrictional surfaces, the abrasion of the frictional surfaces isincreased. However, it has now been found that an electric currentbrings about an effect improving the wear resisting property of thefrictional surfaces, contrary to the previous belief, if appropriateadditives are provided in the lubricating oil.

It is, therefore, one object of the present invention to provide alubricating process for metal frictional surfaces, wherein additives areprovided in the lubricating oil, whereby the activity of the adsorbedmolecules on the frictional surfaces is accelerated by an electriccurrent. The mixture of lubricating oil and additives is used as alubricant on the frictional surfaces, and a film of metallic compoundshaving good lubricating performance is formed by the electric currentwhereby, remarkably, the wear resisting properties of the frictionalsurfaces are caused to increase.

Various lubricants of different kind bring about good lubricatingconditions by an electrolytic polishing action.

As additives, organic phosphite compounds or other organic compounds areeffectively used. The amount of additives, however, is effective below5%, depending upon the type of the additives and base oils used.

As an electric current, D.C. (direct current) is preferable, however,alternating current may also be applied. An adequate value of theelectric current to be practically applied is dependent upon the surfacepressure, the sliding speed, the finished condition, the dimensionalarea of the frictional surfaces, as well as the type of frictionalmetals and additives.

The values of the electric current are, in general, a few volts at llamperes, since a large electric power is not necessary. Consequently,expenses required for the additives and the electric power consumptionare considerably reduced in accordance with the present invention.

As the result of an abrasion test by using an abrasion testing machine(Timken type, four-ball tester), under the best conditions, the abrasionhas been reduced, according to the present invention, about 50% and thepressure bearing capacity has been increased about 25% in comparisonwith the condition, if no electric current is applied. Also, in a wiredrawing test of a piano wire, the drawing force is reduced by Thus, ithas been found that the present manner of operation is very useful, asto the increase of abrasion resistance of a die and the reduction of theapplied power.

The present lubricating process is applicable to various slidingsurfaces, such as to a unit of a shaft and a bearing, an engagingsurface of a worm gear and a worm wheel, etc. and has the advantage ofraising the abrasion resistance of these rotating surfaces.

This process is also applicable to a wide range of processes formetal-working lubrication, such as wire drawing, pipe drawing, threadrolling, extrusion and blanking, and serves the purpose of increasingthe abrasion resistance of tools and of decreasing the working power.

nited States Patent 0 It is one of the advantageous features of thepresent invention that the process can be practiced usefully by simplymounting a small electric equipment on already existing equipment orapparatus.

With this and other objects in view, which will become apparent in thefollowing detailed description, the present invention will be clearlyunderstood in connection with the accompanying drawings, in which:

FIGURE 1 is a front elevation partly in section of a bearing forpracticing the process of the present invention;

FIG. 2 is a front elevation partly in section of a wire drawingapparatus for practicing the present invention;

FIG. 3A is a front elevation of a construction of Timken type abrasiontesting machine used in a fundamental abrasion experiment in the presentinvention;

FIG. 3B is a side view of the Timken type abrasion testing machine;

FIG. 4 is a diagram of one example of experimental results effected byusing a Timken type abrasion testing machine; and

FIG. 5 is a diagram of one example of experimental results obtained byan application of the method to wire drawing.

Referring now to the drawings, FIG. 1 shows one example of theapplication of the process of the present invention to a bearingcomprising bearing housings 1 and 2, a shaft 3 and a bearing member 4.An oil ring 5 is inserted and a lubricant 6 is fed into the bearinghousings 1 and 2. Electric current flows to the bearing housing 1 bymeans of a lead wire 7 connected with the bearing housing 1 and thenpasses. to a lead wire 8 connected with hearing housing 2 through thebearing member 4, the friction surfaces and the shaft 3.

Referring again to the drawings, FIG. 2 shows one example of theapplication to a wire drawing machine, wherein a die 9 is supported by adie holder 10 and includes a winding drum 11 of a wire drawing machine.Rollers 12, 13 and 14 are fixed to a lubricant box 15. The latter ismounted on a frame 20 of the wire drawing machine insulated electricallyby an insulator 16. A wire 17 passes through the lubricant box 15 byusing the rollers 12, 13 and 14, so as to be covered on its surface withlubricating oil. The wire 17 then passes through the die 9, to be woundon the winding drum 11.

The electric current flows from a lead wire 18 to a wire 17, and passesthrough the rollers 12, 13 and 14 fixed on the lubricant box 15 and thenreaches the lead wire 19 through the friction surfaces between the wire17 and the die 9.

The results of a fundamental abrasion test and an applied experiment inconnection with this process will now be described for each of theexamples.

FIGS. 3A and 3B show a partial schematic diagram of a Timken typeabrasion testing machine used in the fundamental abrasion test. Thistesting machine has been equipped with a torque pick-up using a straingauge.

FIGS. 3A and 3B disclose specimens 21 and 22, one being a roller 31 (10mm. (15 x 10 mm.) and the other being a ring 22 (40 mm. The ring 22rotates while being dipped into a lubricant in an oil tank 23. Theroller 21 is attached to a lever 24 and the rotating ring 22 issubjected to a load by a weight 25 suspended at one end of the lever 24.The electric current flows to the frictional surfaces between the roller21 and the ring 22 through contact points 26 and 27.

FIG. 4 discloses a diagram of one example of experimental results byusing the testing machine set forth above. This experiment has beencarried out with a sliding speed of 28.9 m./min. and the amount of wearof the roller has been measured after a sliding distance of 433 m. Inthe diagram, the ordinate shows a volume of wear of the roller and theabscissa shows the load.

The electric current used was a full-wave rectified D.C. As a lubricant,a motor oil, to which 1% of organic phosphite compound has been added,was used. As to the roller and ring material applied in the experiment,a high carbon chromium bearing steel was used. It has been clearlyobserved that the wear was definitely reduced by the flow of an electriccurrent. The coefficient of friction was also reduced more or less(0.01).

FIG. 5 discloses a diagram of one example of experimental resultsobtained by the application of this method to wire drawing.

A motor oil, to which 5% of organic phosphite compound has been added,was used as a lubricant. The current which was used was rectified D.C.in the same manner as in the above example. A piano wire, having acarbon content of 0.71%, which was subjected to a first drawing on adiameter of 3.04 mm. and then drawn through two dies to a diameter of2.65 mm., in order to provide a finished-surface condition, was used.

This piano wire was drawn through a tungsten carbide die of a half angle5 to a diameter of 2.40 mm. (reduction of area 18%).

Drawing speeds were varied and the measured results of the drawingforces for each drawing speed are shown in FIG. 5. A coefficient offriction was calculated from the formula of the drawing force derived byP. W. Whitton.

This figure shows clearly that the drawing force is decreased by theflow of current. The reduction of the drawing force teaches that thecoefiicient of friction between the wire and the die is decreased.

In order to examine the cause of the reduction of the friction and theabrasion, the observation of electron difiraction phenomena on thefrictional surfaces was performed by using motor oil, to which organicphosphite compounds have been added, as a lubricant.

As the result of the above, it is found that when no current flows onthe frictional surfaces Fe P and FeP exist on the frictional surfaces;however, when electric current flows across the frictional surfaces, adiffraction pattern of Fe l and FeP appears clearly. Additionally,

i it is found that a diffraction pattern of FePO -2H O and 2Fe O P O -2HO, which were not found, if no electric current flows, appears clearly.Consequently, it is considered that the formation of a film of metalcompounds on frictional surfaces is accelerated by the how of theelectric current.

While I have disclosed one embodiment of the present invention, it is tobe understood that this embodiment is given by example only and not in alimiting sense, the scope of the present invention being determined bythe objects and the claims.

I claim:

1. A process of lubrication for metal frictional surfaces comprising thesteps of adding up to about 5% of organic phosphite compounds tolubricating oil applied to frictional surfaces, and

passing a substantially uniform electric current across said frictionalsurfaces and through said lubricating oil with said added compounds inorder to initiate and to accelerate the formation of a film of metalcompounds on said frictional surfaces, thereby increasing thelubrication performance of said lubricating oil and reducing thecoefficient of friction between said frictional surfaces.

2. The process, as set forth in claim 1, wherein said step of passingelectric current through said mixture is performed by direct current.

3. The process, as set forth in claim 1, wherein said step of passingelectric current through said mixture is performed by alternatingcurrent.

References Qited by the Examiner UNITED STATES PATENTS 2,661,825 1/1949Winslow 192-215 3,052,316 9/1962 Praberger 1841 3,072,444 1/1963 Klass3081 LAVERNE D. GEIGER, Primary Examiner.

MILTON KAUFMAN, Examiner.

1. A PROCESS OF LUBRICATION FOR METAL FRICTIONAL SURFACES COMPRISING THESTEPS OF ADDING UP TO ABOUT 5% OF ORGANIC PHOSPHITE COMPOUNDS TOLUBRICATING OIL APPLIED TO FRICTIONAL SURFACES, AND PASSING ASUBSTANTIALLY UNIFORM ELECTRIC CURRENT ACROSS SAID FRICTION SURFACES ANDTHROUGH SAID LUBRICATING OIL WITH SAID ADDED COMPOUNDS IN ORDER TOINITIATE AND TO ACCELERATE THE FORMATION OF A FILM OF METAL COMPOUNDS ONSAID FRICTIONAL SURFACES, THEREBY INCREASING THE LUBRICATION PERFORMANCEOF SAID LUBRICATING OIL AND REDUCING THE COEFFICIENT OF FRICTION BETWEENSAID FRICTIONAL SURFACES.